Creative Imagination

We value science fiction because an imaginative sf writer can display the implications, technical, psychological, social etc, of any premise which may be:

a single technological advance;
a plausible near future scenario;
a longer term speculation;
a unique and original idea;
a fairly basic and obvious idea which can nevertheless be shown to have unexpected and surprising implications.

Poul Anderson did this a lot. In a single short story: would technologically superior humanoid aliens conquer Earth militarily? Why not instead sell their military services to the highest bidder among terrestrial governments, thus becoming immensely rich in terrestrial currencies, thereby becoming the new economic rulers of Earth without having to destroy the defence systems of each country first? Anderson suggests that they might do this before anyone on Earth realised what was happening. I doubt that but I suspect that they might do it before the relevant governments had realised (or even cared?) what was happening.

Three Anderson novels each present a comprehensive development of a specific premise.

Tau Zero: What happens when a slower than light interstellar spaceship accelerates uncontrollably at relativistic speeds? (The ship and its crew pass between clusters of galaxies and outlast this universe.)

World Without Stars: all human life spans are extended indefinitely and a star between galaxies has an inhabited planet that can be visited by a faster than light ship; some inhabitants regard our galaxy, their only night time heavenly body, as God.

After Doomsday: interstellar explorers return to the Solar System to find that all life on Earth has been destroyed. What next?

Anderson made several original contributions to the time travel concept:

a Time Patrol to prevent time travellers from changing history (but the Patrol must then contend with quantum fluctuations not caused by time travellers, fluctuations that would prevent order and consciousness, and preventing them turns out to be the Patrol's real purpose);

several ingenious applications of the circular causality paradox;

physical corridors along which it is possible to walk or drive to the past or future;

time travel as a psychic power, not requiring a vehicle or a corridor;

some psychic time travellers want to witness events like the Crucifixion so other travellers attend such events merely to meet fellow travellers;

a time traveller moving forwards, then backwards, along the world line of a slower than light interstellar spaceship can report on the outcome of the voyage before its departure.

I had thought of that last idea but, of course, was not able to work it into a novel as Anderson did.